A particular type of inflatable vehicle occupant restraint is commonly referred to as an air bag. An air bag is stored in a vehicle in an uninflated condition. When the vehicle experiences a collision-indicating condition of at least a predetermined threshold level, inflation fluid is directed to flow from a source of inflation fluid into the air bag. The inflation fluid inflates the air bag to an inflated condition in which the air bag extends into the vehicle occupant compartment. When the air bag is inflated into the vehicle occupant compartment, it restrains movement of a vehicle occupant to help protect the occupant from forcefully striking parts of the vehicle as a result of the collision.
The air bag is typically mounted in the vehicle as a part of an air bag module. In addition to the air bag, the module includes an inflator and a reaction canister. The inflator comprises the source of inflation fluid for inflating the air bag. The reaction canister contains the air bag and the inflator, and has a deployment opening through which the air bag emerges from the reaction canister when it is being inflated.
A deployment door extends over the deployment opening in the reaction canister to conceal the air bag and the other parts of the module from the vehicle occupant compartment. The deployment door may be a part of the module. Alternatively, the deployment door may be a part of a trim panel on the vehicle structure in which the module is mounted. For example, the deployment door may be a part of a trim panel on the vehicle instrument panel.
When the inflator is actuated, the reaction canister directs the inflation fluid to flow from the inflator into the air bag. As the inflation fluid enters the air bag, it moves the air bag outward from the reaction canister through the deployment opening and forcefully against the deployment door. A closure portion of the deployment door is ruptured by the force of the fluid pressure in the air bag. As the air bag continues to move outward against the deployment door, it forcefully deflects a hinge portion of the deployment door so as to move the deployment door pivotally away from the deployment opening. The deployment door is thus opened and moved pivotally out of the path of the air bag as the air bag is inflated outward from the reaction canister through the deployment opening and into the vehicle occupant compartment.